(1) Field of the Invention
The present invention relates to a sandwich glass used in the front glass of automobile and other window glasses.
(2) Description of the Prior Art
Polyvinylbutyral series resins have hitherto been commonly used in the intermediate layer of sandwich glass. However, polyvinylbutyral series resin is thermoplastic, and has various problems in the production of sandwich glass and in the resulting sandwich glass.
That is, the use of the resin has the following drawbacks.
(1) A sticking operation for glass plates must be carried out at a temperature higher than the softening temperature of the resin.
(2) Bubbles are sometimes formed in the intermediate layer during the sticking operation for glass plates, and when two glass plates have been once stuck to each other through the intermediate layer, it is substantially impossible to peel off the glass plates from each other.
(3) After sticking operation, glass plates sometimes move or bubbles are formed due to heat.
(4) The resin is insufficient in the adhesive force, and therefore when the resulting sandwich glass is broken due to impact, the glass plates are sometimes peeled off from the intermediate layer to cause scattering of broken glass pieces.
(5) The adhesive force of the resin deteriorates due to the presence of water with the lapse of long period of time.